Currently, techniques capable of proliferating cells, such as differentiated cells and stem cells in large scale in a short period of time are needed especially in the field of regenerative medicine. In regenerative medicine, procedures are adopted, in which autologous cells (in particular, stem cells) collected mainly from patients are cultured, proliferated and/or differentiated extracorporeally and the regenerated tissues are transplanted. In so doing, in order to minimize aggravation of patients' diseases, various cells such as differentiated cells and stem cells must be proliferated in vitro or otherwise in large quantity in a short period of time. In addition, when tissues are damaged, together with the proliferation of cells involved in such tissues in large quantity in a short period of time, the migration activities of such cells must be increased, in order to repair the tissues efficiently.
On the other hand, the present inventors, with a view that fauna and flora go well with each other, have been conducting researches focused on white rice, which is our principal foodstuff and has the highest safety. Incidentally, during such researches, the inventors have found that water extracts and the like of the material have excellent cell-proliferating and tissue-repairing functions and already filed a patent application concerning the subject matter (Patent Reference 1, PCT/JP2005/000261).